Lesson Summary
Students will discuss human output of
greenhouse gasses and then calculate the amount
of CO2 that their family cars produce per gallon.
Prior Knowledge & Skills
• Data interpreting skills
• Knowledge of greenhouse gasses and the
greenhouse effect
AAAS Science Benchmarks
The Nature of Technology
Issues in Technology
Human Society
Global Interdependence
The Mathematical world
Symbolic Relationships
Shapes
Habits of Mind
Communication Skills
NSES Science Standards
Earth and Space Science
Structure of the Earth System
Science in Personal and Social Perspectives
Natural Hazards
NCGE Geography Standards
Environment and Society
Standard 14
University Corporation for Atmospheric Research
Learn: Atmospheric Science Explorers
http://www.ucar.edu/learn/
Teaching Time: 1 hour and 15 minutes
Materials
• Graphs and charts of greenhouse gases
and human activity (some provided; you
may want to look for other or encourage
your students to do so)
• City map
• Calculator
Advanced Planning
Preparation Time: ~10 minutes
1. Review the instructions
2. Gather the necessary supplies.
Recommended Reading: (attached)
• Background
Activity 20 Teacher Guide: Human Activity and Climate Change
Human Activity and Climate Change
Modified with permission from Global Climates - Past, Present, and Future, S. Henderson, S.
Holman, and L. Mortensen (Eds.), EPA Report No. EPA/600/R-93/126. U.S. Environmental
Protection Agency, Office of Research and Development, Washington, DC., pp. 91 - 94.
In this activity, students will examine graphs of GHG emissions and their increases associated
with human activity. They will focus on
,
,
, CFCs, and . Students will calculate
some personal contributions to
emissions. If you have been using other activities from the
Global Climate Change section of this Web site, you may find this activity is a good culmination
to determine if students have absorbed enough to discuss the issue and connect it to what they do.
Background
Most scientists believe that human activity is altering the composition of the atmosphere by
increasing the concentration of greenhouse gases (GHGs). Greenhouse gases occur naturally in
the atmosphere and their presence results in what atmospheric scientists call the greenhouse effect.
It is important to remember that the greenhouse effect is what keeps the earth warm enough to
be habitable. The current concern is directed at an enhanced greenhouse effect, one that would
put more heat-absorbing gases into the atmosphere, thereby increasing global temperatures.
The enhanced greenhouse effect has been linked to increased GHG emissions from human activities.
Nitrogen (78%) and oxygen (21%) constitute 99% of the dry atmosphere. The rest of the
gases, including GHGs, are collectively classified as "trace" gases due to their low concentrations.
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Activity 20 Teacher Guide: Human Activity and Climate Change
The recent attention given to the greenhouse effect and global warming is based on the
recorded increases in concentrations of some of the greenhouse gases due to human activity.
Of particular interest are water vapor, carbon dioxide, methane, nitrous oxide, chlorofluorocarbons,
and ozone. With the exception of chlorofluorocarbons, all of these gases occur naturally and are
also produced by human activity.
Water vapor is the most important GHG on the planet. Unlike most of the other atmospheric
gases, water vapor is considered to be a 'variable' gas; that is, the percentage of water vapor in
the atmosphere can vary greatly depending on the location and source of the air. For example, over
the tropical oceans, water vapor may account for 4% of the total volume of gases, while over deserts
or at high altitudes, it may be nearly absent. Water vapor absorbs heat readily. When discussing
gobal warming, however, people often don't consider water vapor. Why not? The main reason is
that human activity is not directly changing water vapor content. However, we do directly influence
other GHGs. Although other GHGs are individually less important than water vapor, increasing
their concentrations may affect global climate in significant and measurable ways.
) is considered the most important human-influenced GHG.
Carbon dioxide (
Scientific measurements reveal an unmistakable global increase that is rapid and escalating.
This increase arises primarily from the burning of fossil fuels (motorized vehicles, electric power
plants, and homes heated with gas or oil) and the burning and clearing of forested land for
agricultural purposes.
) is largely a product of natural biologic processes, but its output can be accelerated
Methane (
is emitted from the decay of organic matter in waterlogged soils (for
by human activities.
example, wetlands and rice paddies) and from the digestive tracts of grazing animals (for
example, ruminants). The additions from human activities include the expansion of rice agriculture,
the increased number of livestock, the increased number of landfills, and leakage from natural
gas pipelines.
Chlorofluorocarbons (CFCs) have no natural source; they are produced entirely by human
activity. CFCs have historically been used widely as refrigerants in air conditioners,
refrigerators, freezers, and heat pumps. They are found in some foam plastics and used in
some electronics manufacturing. Even though CFC production has been vastly reduced,
these compounds remain in the atmosphere for a long time; we shall see their effects as GHGs
for many years.
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Activity 20 Teacher Guide: Human Activity and Climate Change
Nitrous oxide (
) is a naturally occurring GHG, which has increased significantly in recent years
due to human activity.
is emitted from coal-burning power plants and can be released from
the breakdown of chemical fertilizers in the soil.
Ozone ( ) is also a greenhouse gas. It is important not to confuse the presence of the ozone in
the stratosphere (a good thing) with the presence of ozone in the troposphere (a bad thing). In
the troposphere, ozone can be a major component of urban smog − damaging crops and
aggravating respiratory problems as well as enhancing the greenhouse effect.
The concentrations of these GHG are increasing (although, thanks to recent global agreements,
CFCs are being largely eliminated and their concentrations have begun to drop in the
lower atmosphere). The emissions are not uniformly distributed globally. Most of the emissions
come from the more developed countries, where power generation, power consumption, and
living standards are highest.
In this activity, students will examine graphs of GHG emissions and their increases associated
,
,
, CFCs, and . Students will calculate
with human activity. They will focus on
some personal contributions to
emissions.
Learning Goals
1. Students will be able to identify sources of the major greenhouse gases and identify the current
trends in atmospheric concentrations.
2. Students will be able to calculate greenhouse gas emissions on personal and larger scales.
Alignment to National Standards
National Science Education Standards
●
Life Science, The Interdependence of Organisms, Grades 9 to 12, pg. 186, Item #5: "Human beings
live within the world's ecosystems. Increasingly, humans modify ecosystems as a result of
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Activity 20 Teacher Guide: Human Activity and Climate Change
population growth, technology, and consumption. Human destruction of habitats through
direct harvesting, pollution, atmospheric changes, and other factors is threatening current
global stability, and if not addressed, ecosystems will be irreversibly affected."
Benchmarks for Science Literacy, Project 2061, AAAS
●
●
The Physical Setting, Processes That Shape The Earth, Grades 6 to 8, pg. 73, Item #7:
"Human activities, such as reducing the amount of forest cover, increasing the amount and variety
of chemicals released into the atmosphere, and intensive farming, have changed the earth's
land, oceans, and atmosphere. Some of these changes have decreased the capacity of the
environment to support some life forms."
The Living Environment, Interdependence of Life, Grades 9 to12, pg. 117, Item #3: "Human beings
are part of earth's ecosystems. Human activities can, deliberately or inadvertently, alter the
equilibrium in ecosystems.
Grade Level/Time
●
Grade level: 6 to 9
●
Time:
❍
Teacher introduction to human activities and GHG: 20 minutes
❍
Student activity: 40 minutes
❍
Student discussion: 15 minutes
Materials
●
●
Graphs and charts of greenhouse gases and human activity (some provided below; you may want
to look for others or encourage your students to do so)
City map
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Activity 20 Teacher Guide: Human Activity and Climate Change
●
Calculator
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Activity 20 Teacher Guide: Human Activity and Climate Change
Procedure
1. Brainstorm possible human sources of GHGs. Where do these gases come from? Are the
sources common all over the world or are some areas larger sources than others?
2. Read and discuss the charts and graphs. How does the information support or contradict the
ideas formed during the brainstorming session?
3. Encourage the students to compare the GHG graphs with other graphs (for example, global
temperature and human population increases) during the same time span. Encourage them to come
up with their own comparisons. What kinds of trends do they predict? Can seemingly upward trends
be reversed?
4. Ask students to discuss global emissions of GHGs. For example, the United States has only a
small percentage of the world's population but emits a disproportionate share of the global
.
China has a population of over a billion people. What would happen if China "developed" to the
point where most families owned an automobile that emitted
?
5. Calculate the personal/family/class contribution of
❍
due to vehicle use:
Using a city map (if necessary), have each student estimate the distance from their home to school
in miles.
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Activity 20 Teacher Guide: Human Activity and Climate Change
❍
❍
❍
❍
❍
❍
Have each student identify their type of family vehicle based on the types listed in the table below.
Have each student calculate the amount of gas used weekly if they rode to and from school everyday
in a private car. To do this:
■
Add up the total number of miles for 10 round trips to school (remember, each time they are dropped
off at school, the driver has to drive home, so there are 2 round trips a day)
■
Divide the total by the miles per gallon to determine the gallons of gas burned
■
Multiply the
■
Example: If you live 4 miles from school, your car travels 16 miles per day to drop you off and pick
you up, or 80 miles per week. At that mileage, a full-size car will burn 5 gallons of gas per week.
Five gallons of gas will produce 100 pounds of
every week.
released per gallon
Calculate the class total as if everyone rode to school in a private vehicle.
Have students who ride the bus do the same calculations again, using the figures for the bus
and dividing the total
released by the approximate number of students that ride on the bus.
Determine how many students walk or bike to school. They do not contribute additional
to and from school.
to get
Now re-calculate the class total based on the type of transportation actually used by students.
Compare the results. How much difference is there?
Vehicle
MPG
Pounds
per gallon
Compact car
24
20
Full-size car
16
20
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Activity 20 Teacher Guide: Human Activity and Climate Change
*Buses add more
Truck/Van
13
21
Bus
8
22*
per gallon, but they carry more passengers, so be sure to consider contribution by passenger,
not just vehicle.
Assessment Ideas
The disparity between population size and GHG emissions is large, but very difficult to address
without altering the lifestyle of the highest GHG emitters, at least in the short term.
emission common in the U.
As a written (or oral) assignment, ask students to pick one source of
S. and argue in support of a 50% reduction in
emissions from that source. To do so, they
must explain:
●
The sources
●
How they propose to achieve the reduction
●
The impact of the reduction on American lifestyles and/or economy
●
How the reduction might slow the build-up of GHGs
Alternatively (or as a companion assignment), ask students to imagine that they live in a
developing country. Have them argue that they should be allowed to continue to increase
GHG emissions as they pursue a better material standard of living for their citizens.
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Activity 20 Teacher Guide: Human Activity and Climate Change
Modifications for Alternative Learners
●
English Language Limited students might have difficulty comparing GHG gas charts with other
graphics (the connections may be a bit abstract in step 3). Teachers should be very clear and
consistent in connecting one chart to another in terms of simple cause-and-effect relationships.
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